<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- <style>
        body > * {
          width: 980px;height: auto;margin: 0 auto;margin-top: 10px;
          border: 1px solid #000;padding: 5px;
        }
        header {height: 50px;}
        section {height: 300px;}
        footer {height: 30px;}
        section > * {height: 100%;border: 1px solid #000;float: left;}
        aside {width: 250px;}
        article {width: 700px;margin-left: 10px;}
      </style> -->
       <style>
        body > * {
          width: 95%;height: auto;margin: 0 auto;margin-top: 10px;
          border: 1px solid #000;padding: 5px;
        }
        header {height: 50px;}
        section {height: 300px;}
        footer {height: 30px;}
        section > * {height: 100%;border: 1px solid #000;float: left;}
        aside {width: 25%;}
        article {width: 70%;margin-left: 10px;}
      </style>
</head>
<body>
    <header>header</header>
    <nav>nav</nav>
    <section>
        <aside>aside</aside>
        <article>article</article>

    </section>
    <footer>footer</footer>
</body>
</html>